chiometric balances made on both reactants and products demonstrated that no other substances are involved in the reaction, at least within the accuracy of the analytical methods. This was true for the completed reactions as well as those that could be monitored with time (pH > 8.35).The reaction rate constant kx is independent of pH in the range of 9.5-11.6, ionic strength up to 0.04, initial concentrations of nitrite ranging from 1 to 17 mg/L as N and chlorine from 2.3 to 140 mg/L as Cl2, and finally

No abstract

RBGALLA. 1983. Hydrologic confro1 of lake susceptibility to acidification, Can. J. Fish. Aquat. Sci. 4: 1896 -1904.Two hundred and seventy-five lakes were sampled in the summer of 1979 to assess the factors controlling susceptibility of northcentral Wisconsin lakes to acidification. In addition to direct evaluation of m a n s and ranges of the physical and chemical characteristics, a cluster analysis was carried out using alkalinity, color, a d chlorophyll a data. Three well-defined clusters emerged that appeared to be controlled by hydrology: Adominated by surface runoff; Bdominated by groundwater; Cdominated by precipitation. Relationships between morphometric, hydrologic, and terrigensus factors that can influence lake water quality and susceptibility were further examined by discriminant analysis of 18 watershed properties across the three lake clusters. Hydrologic factors were most important in differentiating the low alkalinity and high alkalinity lakes. The potentially sensitive low alkalinity lakes in northcentral Wisconsin lack surface inlets or outlets and their chemistry is closely associated with precipitation chemistry. EILERS, J. M., G. E. GLASS, K. E. WEBSTER, AND j. A. RBGAEEA. 1983. Hydrologic control of lake susceptibility to acidification. Can.

We examined relations between mercury concentrations in walleyes Stizostedion vitreum and the characteristics of clear-water Wisconsin lakes, which spanned a broad range of pH values (5.0-8.1) and acid-neutralizing capacities (-9 to 1,017 jieq/L). Total concentrations of mercury in axial muscle tissue of walleyes (total length, 25-56 cm) varied from 0.12 to 1.74 jig/g wet weight.Concentrations were greatest in fish from the eight lakes with pH less than 7.0; concentrations in these fish equaled or exceeded 0.5 /ig/g in 88% of the samples analyzed and 1.0 Mg/g in 44%. In the five lakes with pH of 7.0 and above, concentrations exceeded 0.5 Mg/g in only 1 of 21 walleyes. Multiple regression revealed that lake pH and total length offish accounted for 69% of the variation in mercury concentration in walleyes. Regression models with total length and either waterborne calcium or acid-neutralizing capacity as independent variables accounted for 67% of the variation in concentration. The observed differences in fish mercury concentration between the low-pH and high-pH lakes could not be logically attributed to differences in growth rate or diet among the walleye populations. Moreover, it is improbable that mercury influxes to the low-pH lakes were greater than those to the high-pH lakes, because of the close proximity and spatial interspersion of low-and high-pH lakes. We attributed the observed pH-related trend in mercury concentration in walleyes to variation among lakes in within-lake processes that affected the production and bioavailability of methylmercury.

No abstract